Index Tracking vs Active Management: What the Evidence Says

The choice between an index fund and an actively managed one is usually argued as a matter of belief. It is mostly a matter of arithmetic, and the arithmetic works in a way that surprises people.

What each is trying to do

An index fund tracks an index. It does not try to pick which companies will do better; it holds what the index holds, in the proportions the index holds them. Few decisions means low costs.

An actively managed fund has a manager who chooses. The aim is to beat the index. Research teams, analysts and more frequent trading mean higher costs.

The arithmetic that frames the whole debate

Before costs, investors in aggregate are the market. Every share is held by someone. So for every rand that beats the market average, another rand must lag it — not because managers are unskilled, but because they collectively hold everything there is to hold.

After costs, the average actively managed rand must therefore trail the index by approximately what it paid in fees. That is not a claim about talent. It is addition.

The practical consequence is demanding: an active manager does not merely have to be better than average. They have to be better by enough, every year, to cover their own fee before you are a cent ahead.

What long-run studies find

Surveys that measure active funds against the benchmark they are actually meant to beat find a consistent pattern worldwide and in South Africa: over five, ten and fifteen year periods, the majority of active funds trail their index.

Two details make that finding stronger than it first appears.

Survivorship. Funds that perform badly get closed or merged away. A list of funds that exist today therefore looks better than the experience of investors who chose from the list as it stood ten years ago.

Persistence. Managers who outperform in one period are not reliably the same managers who outperform in the next. This is the crux: even if genuine skill exists, identifying it in advance is the hard part, and past performance does that job poorly. Selecting last decade's winner is not a strategy, it is an extrapolation.

Costs, concretely

The total expense ratio is the percentage deducted from your investment each year. It sounds small and it compounds against you exactly as returns compound for you.

Take R500,000 invested for twenty years at the same gross return. A one percentage point difference in annual costs does not cost you one percent — it costs a share of every year's growth, and the growth that money would itself have produced. Over two decades the gap runs well into six figures.

Unlike returns, costs are known in advance and entirely within your control. That asymmetry is the strongest practical argument in the whole debate.

Look at both the TER and the transaction costs on the fund fact sheet. The total investment charge is the number that matters, not the headline management fee.

A worked example of the fee drag

Take R500,000 invested for twenty years, growing at 9% a year before costs.

At a 0.25% total annual cost, the effective growth rate is about 8.75% and the money reaches roughly R2.68 million.

At a 1.25% total annual cost, the effective rate is about 7.75% and it reaches roughly R2.22 million.

The gap is about R460,000 — comfortably more than the original investment — from a difference of one percentage point a year on the same underlying returns.

Two honest qualifications, because this comparison is often overstated. First, it assumes the cheaper fund delivers the same gross return; a manager who genuinely adds more than their fee changes the answer. Second, quoting the gap as a share of the final pot ("fees take a third of your money") overstates the effect at more typical horizons and contribution patterns. Run it on your own numbers and your own horizon rather than trusting a slogan in either direction.

What survives the qualifications: the cost is certain and the outperformance is not.

How to read a comparison honestly

Most fund comparisons you will encounter are constructed to make a point, so it helps to know what to look for.

Check the period. Any three-year window can be chosen to favour a strategy. Five years is a minimum; ten is better, and should span at least one significant decline.

Check the benchmark. A fund compared against a benchmark that does not reflect its mandate is being flattered. A local equity fund measured against cash is not telling you anything useful.

Check whether the manager is the same person. A ten-year record built by someone who left three years ago belongs to them, not to the fund.

Check the fund's size. A strategy that worked on a small asset base does not always survive being ten times larger, particularly in a market with limited liquidity.

Watch for closet indexing. A fund that largely mirrors the index while charging active fees is the worst combination available — you pay for decisions that are not being made. Comparing the fund's top holdings against the index's is a quick check anyone can do.

The case against is not absolute, and there are situations where paying for a manager is defensible.

Less efficient markets. Where fewer analysts cover a segment and information is unevenly distributed, there is more room for research to add value than in a heavily covered large-cap market.
A specific outcome rather than the market return — a fund explicitly managed for lower volatility, or for income, is doing something an index does not.
A mandate that excludes something you do not wish to own.

In all three the fee question remains. You should be able to say why this manager, in this mandate, is likely to earn the difference — and "they did well recently" is not that reason.

The South African wrinkle

Two local considerations change the shape of the decision.

Concentration. The main local index is dominated by a small number of very large companies, with heavy weightings to resources and a couple of global names. Tracking it is not as diversified as tracking a broad world index, so "index investing" in a South African context needs the question: which index?

Regulation 28. If the money sits in a retirement fund, limits apply to how much may be held offshore and in each asset class. That constrains both index and active options equally, but it is why a retirement annuity portfolio looks different from a discretionary one.

What to do in practice

Build a broad, cheap core. A globally diversified index fund is a reasonable centre of gravity for most people, and it answers the concentration problem above.
Add active with a reason, not with a performance table.
Compare against the right benchmark. A local fund beating a local index while a world index beat both has not served you well.
Look after tax too. More trading inside a fund can mean more taxable events. Inside a tax-free savings account or a retirement annuity that question falls away — see tax-free savings accounts.
Then leave it alone. Switching between approaches on recent performance is the single most reliable way to capture the worst of both.

The behaviour gap, which is larger than the fee gap

The difference between what a fund returns and what its investors earn is often bigger than the difference between index and active funds in the first place.

It comes from timing. Money flows in after a strong run and leaves after a weak one, so investors buy high and sell low with remarkable consistency. A mediocre fund held for twenty years beats an excellent fund entered and exited three times.

That is the strongest practical argument for a simple, cheap core: not that it is theoretically optimal, but that it is the kind of portfolio a person can hold through a bad year without acting. A plan you can keep beats a better plan you cannot. See rand-cost averaging explained for the mechanism that makes holding easier.

Frequently asked questions

Are ETFs the same as index funds?

Not quite. An ETF is a structure that trades on an exchange; most ETFs track an index, but some are actively managed. Check the mandate rather than the wrapper.

If everyone indexed, would it stop working?

A fair theoretical objection, but we are nowhere near that point — a great deal of active capital still sets prices every day.

Which index should I track?

For a core holding, a broad global index is simpler and better diversified than a single-country one, particularly given the concentration in the local market.